4.1
In accordance with EM&A Manual, two noise monitoring stations,
namely NMS1 and NMS4 were selected for impact monitoring for the Contract.
Impact noise monitoring was conducted for at least once per week during the
construction phase of the Contract. Appendix
B shows the established Action and Limit Levels for the noise monitoring works.
4.2
Impact noise monitoring was conducted at the 2 monitoring stations under
the Contract, as shown in Figure 3. Table 4.1 describes the locations of
the air quality monitoring stations.
Table 4.1 Location for Air Quality Monitoring Locations
Monitoring Stations |
Location |
NMS1 |
Sha Lo Wan |
NMS4 |
San Tau |
4.3
Table 4.2 summarizes the noise monitoring
equipment. Copies of calibration
certificates are provided in Appendix C.
Table 4.2 Noise
Monitoring Equipment
Equipment |
Model and Make |
Qty. |
Integrating Sound Level Meter |
SVAN 957 |
2 |
Calibrator |
SV 30A |
2 |
Monitoring
Parameters, Frequency and Duration
4.4
Table 4.3 summarizes the monitoring
parameters, frequency and total duration of monitoring. The noise monitoring schedule is shown
in Appendix D.
Table 4.3 Noise
Monitoring Parameters, Frequency and Duration
Monitoring Stations |
Parameter |
Period |
Frequency |
NMS1 NMS4 |
L10(30 min.) dB(A) L90(30 min.) dB(A) Leq(30 min.) dB(A) (as six consecutive Leq, 5min readings) |
0700-1900 hrs on normal weekdays |
Once per week |
Monitoring
Methodology and QA/QC Procedures
¡P
The microphone head of the sound
level meter was positioned
¡P The battery condition was checked to ensure the correct functioning of the meter.
¡P Parameters such as frequency weighting, the time weighting and the measurement time were set as follows:
¡X frequency weighting : A
¡X time weighting : Fast
¡X time measurement : Leq(30 min.) dB(A) (as six consecutive Leq, 5min readings) during non-restricted hours (i.e. 0700-1900 hrs on normal weekdays)
¡P Prior to and after each noise measurement, the meter was calibrated using a Calibrator for 94.0 dB at 1000 Hz. If the difference in the calibration level before and after measurement was more than 1.0 dB, the measurement would be considered invalid and repeat of noise measurement would be required after re-calibration or repair of the equipment.
¡P During the monitoring period, the Leq, L90 and L10 were recorded. In addition, site conditions and noise sources were recorded on a standard record sheet.
¡P Noise measurement was paused temporarily during periods of high intrusive noise (e.g. dog barking, helicopter noise) if possible and observation was recorded when intrusive noise was not avoided.
¡P
Noise monitoring was cancelled
in the presence of fog, rain, and wind with a steady speed exceeding
4.5
The microphone head of the sound level meter and calibrator were cleaned
with a soft cloth at quarterly intervals.
4.6
The sound level meter and calibrator were checked and calibrated at
yearly intervals.
4.7
Immediately prior to and following each noise measurement the accuracy
of the sound level meter shall be checked using an acoustic calibrator
generating a known sound pressure level at a known frequency. Measurements may
be accepted as valid only if the calibration levels from before and after the
noise measurement agree to within 1.0 dB.
4.8
The noise monitoring results are summarized in Table 4.4. Detailed monitoring results
and graphical presentations of noise monitoring are shown in Appendices G.
Table 4.4 Summary Table of Noise Monitoring Results during the Reporting Period
Monitoring Station |
Noise Level, Leq
(30min) dB(A) |
Limit
Level |
|
Average |
Range |
||
NMS1 |
65 |
N/A |
75 dB(A) |
NMS4 |
59 |
N/A |
Remark: +3dB(A) Façade correction included
N/A: Only one noise monitoring was conducted in the reporting period, no
range of noise level is provided.
4.9
All noise monitoring was conducted as scheduled in the reporting period. No Action/Limit Level exceedance was recorded.
4.10
According to our field observations, the major noise source identified
at the designated noise monitoring stations are as follows:
Table 4.5 Observation at Noise
Monitoring Stations
Monitoring Station |
Major Noise Source |
NMS1 |
Air
traffic & marine traffic noise |
NMS4 |
Air
traffic & marine traffic noise |
4.11
Should non-compliance of the criteria occur, action in accordance with
the Action Plan in Appendix K shall
be carried out.